As an audio signal encoding method in the related art, HE-AAC (High Efficiency MPEG (Moving Picture Experts Group) 4 AAC (Advanced Audio Coding)) (International Standard ISO/IEC 14496-3) is known.
In this encoding method, a high frequency feature encoding technology called SBR (Spectral Band Replication) is used (refer to Patent Document 1, for example). According to the SBR, when an audio signal is encoded, SBR information for generating a high frequency component of the audio signal is output together with a low frequency component of the encoded audio signal. More specifically, the SBR information is obtained by quantizing power (energy) of each frequency band called a scale factor band of the high frequency component.
Further, in a decoding device, while the low frequency component of the encoded audio signal is decoded, a high frequency signal is generated using a low frequency signal obtained from the decoding, and the SBR information. As a result, an audio signal including the low frequency signal and the high frequency signal is obtained.